struct PO_DEVICE_NOTIFY_ORDER

typedef struct _PO_DEVICE_NOTIFY_ORDER
{
     UCHAR Locked;
     PDEVICE_OBJECT * WarmEjectPdoPointer;
     PO_NOTIFY_ORDER_LEVEL OrderLevel[8];
} PO_DEVICE_NOTIFY_ORDER, *PPO_DEVICE_NOTIFY_ORDER;

Windows Vista Kernel Structures